Conventional mobile communication systems using wired backbones control a transmit power simply by focusing on improvement of link performance between a BS and a mobile communication terminal in determining a downlink transmit power.
This conventional transmit power control technique is to maximize the total capacity of a link between a BS and a mobile communication terminal, or control a transmit power such that an amount of interference exerted on neighboring BSs and mobile communication terminals is reduced.
However, this transmit power control technique assumes that a capacity of a backbone is sufficient and thus a transmission amount required in a wireless link between a BS and a mobile communication terminal is supportable all the time.
Accordingly, when the conventional transmit power control technique, without considering the capacity of the backbone, is applied to a system in which a backbone of a BS is formed by a wireless link of insufficient capacity, and a capacity of the backbone can be insufficient because of circumstances of a movement and the like of the BS, the backbone causes a bottleneck phenomenon.
Accordingly, there is a problem of providing a quality of service noticeably worse than service expected on the basis of a capacity of a link between a BS and a mobile communication terminal. Also, there is a problem that the degree of user satisfaction in communication can be greatly degraded because of the provision of a quality of service much worse than the expected service.
That is, there is a problem that degradation of a quality of service resulting from the deficiency of a capacity of a backbone takes place when many mobile communication terminals have access to a BS of low backbone capacity without considering backbone capacity in a mobile communication system using a wireless backbone.